High frequency electron tube



Oct. 23, 1956 B. BROWN ET AL HIGH FREQUENCY ELECTRON TUBE 3"Sheets-Sheet 1 Filed Feb. 27, 1953 N r p mw@ w 5m H mmm. M HH 7 wm. UwmN BMM ,a H A :IL F WN E NN E VE N www, mw MN 0 my MMM WWMQMWLTMTMWJMIIII. WIIIIIMIIHLI mi m2, m m v Q LM W .|n n X J m50 Qm www /J uw,mNCm ,mwm m .n WANN QN \N \Q\. llmu www Oct. 23, 1956 B. B. BROWN rs1-AL2,763,326

HIGH FREQUENCTELECTRON TUBE @ned Feb. 27, v1953 3 Sheets-Sheet 2 ORNE YHIGH FREQUENCY ELECTRON TUBE lFiled Feb. 27, 195s 3 sheets-sheer 3ILXVTOR. BARRE/waff 5. B/Pow/v LESL/E'KaVAc/f ND MoH/V .M4 Smc/#m7 TTORNE Y United States Patent HIGH FREQUENCY ELECTRON TUBE Barremore B.Brown, Morristown, and Leslie Kovach, 'Whippany, N. J., and John W.Seachrist, Lancaster, Pa., assignors to Radio Corporation of America,acorporation of Delaware Application February 27, 1953, Serial No.339,316 13 Claims. (c1. 3151-36) This invention relates .to highfrequency electron -tubes in which elements in the tube form an-appreciable portion of a high frequency circuit. More particularlyvthis invention relates to high frequencyelectron tubes wherein theelectrode structure is completely enclosed in avacuum envelope,

v Heretofore such structures have proven extremelycom.- plexfrorn thestandpoint of their manufacture and .have presen-ted serious problems inconnection with providing adequate .adjustment and tuning, cooling ofvarious parts, and a shock-proof structure while maintaining ,simplicityand ease of manufacture as well as an overall high degree .of precision,long life and low cost. In connection with such high frequency devices,the frequency at which the device is intended to operate determines thesize of parts such as electrodes, tuning devices and the like. Thus,size may not readily be varied in accordance `with desired thermaldissipation.

vSerious problems have been encountered in the past in providing astructure having stability over along useful life. One specific problemrelates to .providingcomposite lseals such as glass or ceramic to metalwhich are capable of withstanding the `high temperature ,bakeout processnecessary to long useful ylife and stability. Thus, in the past aninordinate amount of time and cost went into providing an adequatesupport structure vand envelope which heretofore proved to be usefulonly ,with the particular device in hand and no others.

It is therefore a principal object of this invention .to

provide a structure for a high frequency electron 1tube particularly.adaptedfor enhanced merit .and long life.

Another object is the `provision .of `a stem and support structure for ahigh frequency device whereinall composite seals such as ceramic or thelike to-.metal are relatively small and all are located at one part, ofthe device, which structure is adapted for .use ina .wide variety ofhigh frequency electron tubes, and whichstructure is readily fabricatedand tested outside the vacuum envelope of the device in which it is tobe ,ultimatelyl utilized.

Another object .is .the .provision of such .a v.device wherein a stemandmount structure is provided inconjunction with a radio frequencyystructure kadapted yfor adjustment and tuning, vall being arranged toensure enhanced life, lv.as well as ease in manufacture.

Still .another .object is the provision of a :magnetron structurewherein a stem andmount structure -is provided in lconjunction with ahigh frequency structure adapted for adjustment and tuning, all beingarranged to ensure-enhanced life, efficient cooling, as WGH yas ease inmanufacture.

In accordance with this invention a unitary stern and mount structure isprovided suitable for supporting a tuning mechanism as well as theelectrodes of a high frequency .electron tube such as a magnetron; -themount structure ,including a goodV thermal path for cooling'an anode byconduction as well as means for adjusting the tuning of the device. Theseals Yincorporated `in ICC the mount structure which form part of thevacuum envelope lend themselves to pre-.testing prior to sealing-in ofthe device. The mount is sealed to a simple glass envelope, the outlineof which is unbroken by the passage therethrough vof other members.

Still other objects as well as advantages of this in,- vention will beapparent from the following description when read in conjunction with`theaccompanying drawing in which:

Figure 1 is Ia sectional View taken on line 1--1 `of Figure 2 of a,tunable magnetron constructed in laccordance with kthis invention:

Figure 2. is a sectional View thereof taken on the line 2-2 of Figure l;

Figures 3 and 4 are transverse sectional views taken on lines 3 3 and 44, respectively, of Figure l; and

FigureV 5 is vaV plan View of the magnetron partially broken away forconvenience.

One ltype of high frequency electron tube in which this invention isadvantageously used is the magnetron. rIIherefore, while this inventionwill now be described in .detail in connection with such a device, it is-to be understood that this invention is not to be limited to magnetronsbut is also useful in other high frequency tubes.

Referring now to the drawings tin ydetail, .electron de.- vice 10, inthis instance a tunable multi-cavity magnetron, comprises a hermeticallysealed vacuum tight composite glass and metal envelope which, Vas shown,-includes .tubular dielectric bulb 11 of glass. Envelope bulb 11 isunbroken in outline except at one end where it is sealed to .adielectric vdisc or button-like stem member 11 of glass which is sealedat 13 to a member 12 of relatively thin cross-sectional thickness .andwhich is generally tubular. Member 12 is metallic and is constituted ofsuch `metals Ias will readily seal to glass such as 4the rwell known`glass 'sealing alloys. Tubular vmember 12 .extends into envelope bulb11 and at its externalend has an inwardly turned flange brazed vacuumtight at its periphery 14 to an elongated ,tubular vmemberlSintermediate kthe ends thereof. Thus, the member 12 serves las a meansfor joining the glass 4disk 1,1 and the ,tubular metal .member A15 ,inair or lvacuum ,tight relation. As clearly shown, tubular member 15 .hasa thick wall .and is substantially thicker in .cross A.section thantubular member 12. Furthermore, tubular ,member 15 has :one endextending .through tubular member 12 into bulb 11. The composition .oftubular -memberlS is particularlychosen to provide a high conductivethermal path and may be copper or Vthe like. Tubular member 15 `isIconnected adjacent its other end to a massive copper mounting disc 16by means of which electron deviceltl may be rigidly mounted in suitableapparatus.

Coaxiallyfmrounted with respect to tubular member-15 and extendingthrough the .same is elongated tubular member `17 which, as will beVmore fully pointed out hereinbelow, functions as a Ytuning rod and alsoas .an exhaust tubulation. Tubular member -17 is in snug .slidingengagement with a metallic disc 18 through which it extends; disc-,18being connected to tubular member 1S, as indicated, .at the end 19thereof. vOne end of tubular member 17 extends inwardly into bulb 11beyond .the inner end of tubular member 15. The `otheror outer end oftubular member 1-7 extends outwardly beyond inner end thereof formed bya plunger'21 rigidly vcon-Y nected thereto as shown. Adjacent the inneren d of tubular member 17 an annulardisc 22'is mounted thereon andsealed thereto vacuum tight at 23 as by brazing or the like. Theperiphery of disc 22 is connected in a vacuum tight manner to a thinwalled tlexible member 24 which functions as a bellows and which is inturn sealed to the inner end of tubular member 15. As will be moreclearly pointed out, the foregoing arrangement permits mechanicaladjustment to be made between the centrally located tubular member 17and the remainder of the thus far enumerated component parts of electrondevice 10. This follows from the fact that bellows 24 is formed by thethin flexible wall having a plurality of folds as shown which rendersthe same -axially extensible and retractable.

To intermediate tubular member 15 which extends in the region betweenouter member 12 and innermost member 17, a massive highly thermallyconductive support member 25 is connected and as shown bridges bellows24. Specifically, support member 25 is a U shaped yoke having acentrally located aperture in its base through which tubular member 15passes and is joined thereto. Support member 25, as was pointed out inconnection with tubular member 15 and mounting disc 16, is of goodthermal conductive material and is joined to member 15 so as to reduceheat isolation to a minimum.

It may be well to point out at this time that the structure thus fardescribed constitutes a highly useful support and lead-in subassernbly.During the manufacture of electron device 10, bulb 11 and disc 11' areinitially two separate and distinct parts. As most clearly shown inFigures 2 and 3, disc 11 has a plurality of lead-in pins 26 sealedtherethrough and arranged in an annular array having a relatively largediameter. As previously indicated disc 11 is sealed to member 12 andonly after the assembly of electron device is otherwise complete is disc11 joined to bulb 11 by well known glass to glass sealing techniques.One extremely important advantage of the present construction resides inthat only one composite glass to metal seal is involved while theusually troublesome metal to metal seals are not only maintained smallin area but now may be tested to determine the efficiency thereof beforebeing incorporated in a nished electron device. Thus, all the vacuumtight joints of the completed device except the pinch-off of member 17and the seal joining disc 11' to bulb 11 are readily tested. Only suchsubassemblies free of defects are utilized to complete the assembly ofdevice 10, thereby making possible a substantial reduction in the costthereof.

One type of device in which our invention has proven particularlyadvantageous is electron device 10 shown by way of illustration andwhich further includes a cavity resonator 27 which forms a tuning cavityclosely coupled through an iris to a multicavity magnetron anode 28.Cavity resonator 27 has two sets of side walls 29, 29 and an end wall 30having an H-shaped iris opening 31 formed therein. The pair of opposedside walls 29 have extensions 29 (Figure l) which are rigidly bolted tothe free ends of support member 25 and have large areas in contact toform a good heat exchange connection. A pair of opposed spaced apartelongated metallic plates 32 are each connected at one end thereof toend wall 30; iris 31 being located with the bar portion of its H shapeextending centrally through the portion of end wall 30 between plates 32and parallel to the latter. A second pair of metallic plates 33, eachconnected to end wall 30, the corresponding one of opposed side walls 29and one of the plates 32, serve to maintain the latter in parallelspaced relation. As described, cavity resonator 27 when excited has anelectric field distribution therein having maximum intensity orconcentration in the region between parallel plates 32. It is to beunderstood that the walls and plates of resonator 27 are of conductivemetal or the like such as copper.

Each of the opposed side walls 29 has an aperture,

the apertures being in opposed relation with a cupshaped member orshield 34 extending through each of the apertures into the cavity ofresonator 27. Cupshaped members or shields 34 are each connected to andsupported from one of the walls 29' and each has a slot 35 formed in thebase thereof. As most clearly shown in Figure 2, shields 34 form wellsor recesses in walls 29 in each of which an electron gun structure 36 issuspended from a sheet of insulative material such as mica 37 each ofwhich is securely connected to one of the side walls 29. Leads 38 extendin spaced relation` to one lof the electrodes of the guns 36 and attheir other ends are each connected to a leadin pin 26. The leads 38 foreach gun 36 are sandwiched between one of the mica sheets 37 and asecond mica sheet 39 also supported from side walls 29 as shown inFigures 2, 3 and 4. Magnetic pole pieces 40 are mounted one behind eachof the guns 36 and connected to walls 29.

Each gun 36 comprises three spaced electrodes including a cathode 36',an apertured control grid 36" and an apertured accelerating electrode36". The shield 34 of each gun 36 acts as the electron collector for theother n depending on which gun is being operated.

' wave guide As most clearly shown in Figure l, tuning plunger 21 isslidably inserted between parallel plates 32 and has the same width asthe plates. Movement of central tubular member 17 is transmitted toplunger 21, axial movement of which allows tuning over the frequencyrange of the device which may, for example, be from approximately 6575to 6875 megacycles.

Magnetron anode 28 is a conventional multiple vane double strappedstructure comprising an anode block 41 having a cylindrical chamber inwhich are mounted a central cathode 46 and an annular array of radialvanes 41 forming cavity resonators 41" therebetween, as clearly shown inFig. l. Anode block 41 is connected to end wall 30, as well as plates 32and 33, in good heat exchange relationship and is provided with anaperture 41 which opens into one of the resonators 41" and communicateswith iris 31. Thus magnetron anode 28 is closely coupled to cavityresonator 27. Anode block 41 is provided with a second H-shaped iris 42by means of which the magnetron is closely coupled to an output notshown. The output wave guide is readily mounted adjacent the outside ofthe end of bulb 11 and closely coupled through the glass wall to themagnetron anode 28. An annular disc 43 connected to anode block 41carries an annular disc-shaped mica 44 and snubbers 45. The snubbers 45engage the interior surface of bulb 11 and serve to firmly position thefree end of the structure centrally therein. Magnetron anode 23additionally comprises the usual magnetic pole pieces 47. The leads jfor the magnetron electrodes such as the anode, cathode and heater leadsare also joined to lead-in pins 26. This is most clearly shown in Figure5 where lead 4S is shown extending from one end of cathode 46 to one ofthe lead-in pins 26.

While the electronic operation of such devices as electron device 10 isdescribed in considerable detail in an article entitled A 7000 megacycledevelopmental magnetron for frequency modulation by H. K. Jenny,appearing at page 202 of the RCA Review, volume XII, No. 2, dated June1952, it is not believed necessary to treat the subject at such greatlength herein. However, it will be well to point out that duringoperation of such a device the heat generated in anode block 41 isconducted to cavity resonator 27 and in turn conducted to support member25 by way of extensions 29". Similar ly, the heat generated duringoperation of one or the other of the modulating guns 36 is conducted tosupport member 25. As was pointed out, support member 25 affords ahighly conductive thermal path and, together with intermediate tubularmember 15, conducts the heat generated within the envelope of electrondevice 10 to the exterior thereof. The arrangement of lead-in pins' 26about circle having a relatively large diameter affords a highlydesirable electrical isolation between Ithe various leads.

From the foregoing, it is apparent that there is provided a vhighlycompact rigid structure `which lends itself to the high degree ofprecision required in the lmanufacture `of such devices. The structureshown may be readily mounted in the .apparatus with which it coactsWithout requiring any complicated manipulations to be performed. Whilethis invention has been described in great ldetail in connection with atunable multiple cavity magnetron, it .is believed apparent thatapplicants invention is also suitable lfor use with other highAfrequency electron devices wherein the internal structure of the deviceconstitutes appreciable portions of the electrical circuit, therebyprec'luding employment of the usual practice of increasing the size ofsuch elements, as for example kthe anode, in order to improve thethermal dissip-ation characteristic thereof. By arranging the variousleads and the tuning at one end of the envelope, as well as `providingthe required heat dissipation or cooling through the same end, the otherend .of the device is available for coupling to an output circuit suchas a wave guide in an extremely simple manner. Therefore, it is notintended that this invention be limited to the exact construction setforth but to claim all modications thereof that come within the scope ofthe appended claims.

In the claims, the term electrode assembly refers to the electrodessupported bythe stem structure (11, 12, 1S, 17 and 25). As shown in t-hedrawing, this assembly would include one or more of the magnetron anodeblock 2S, cathode 46, tuning .resonator 27 .and plunger 2i, andmodulating guns 36.

What we claim is:

ll. A high frequency electron tube comprising ,a vacuum envelopeincluding a hollow dielectric body, an electrode assembly .and a stemstructure .supporting said electrode assembly in said hollow dielectricbody, said stem structure comprising a dielectric member, an elongatedmetallic tubular member sealed Athrough vsaid ldielectric member, said.dielectric member being sealed to said hollow dielectric body andclosing the same, means including an exhaust tubulationclosing saidtubular member tothe external atmosphere, an array of .lead-in memberssurrounding said tubular member and sealed through said dielectricmember, and -a yoke connected to said tubular member and to saidelectrode assembly, all the members sealed through said envelope beinglocated at the .end portion of said envelope which includes vsaid stemstructure, said electrode assembly being .supported substantially solelyby said tubular member and ,said yoke.

2. A high frequency electron tube comprising :an electrode assembly, avacuum envelope including a stem structure yand a hollow `dielectricbody enclosing said electrode assembly, said stem structure comprising apair of coaxial metallic tubular members, one of said tubular membersbeing open tothe interior of said envelope and `sealed to theatmosphere, means joining said tubular members together in vacuum tightrelation, a support member connected to the other of said tubularmembers and to said electrode assembly and forming substantially thesole support for said electrode assembly, va dielectric member sea-ledin vacuum tight relation with said other tubular member and sealed tosaid dielectric body and closing the same, an array of lead-ins sealedthrough said dielectric member and connected to said electrode assembly,said lead-ins and tubular members forming the sole direct currentconnection through said envelope to said electrode assembly.

i3.. A high frequency electron tube, comprising an electrode assembly,ya vacuum envelope. including -a stem structure and ahollow dielectricbody `open at one lend .and enclosing said yelectrode assembly,Asaid'stem structure `comprising a pair of coaxial metallic tubularmeinber-s, Vthe Ainner one of .said members being open :to the interiorof said envelope vand sealed to the atmosphere, flexible means joiningsaid tubular members -in vacuum tight relation, said -inner .tubularmember being movable with respect to said outer tubular member, theouter one of said tubular members being highly thermally conductive, adielectric member sealed vacuum tight to said hollow dielectric body andclosing the latter, .means joining said dielectric member vacuum tightto fsaid router tubular member, an array of lead-ins sealed through saiddielectric member and spaced around said outer tubular member, a massivemetallic support member connected to said outer tubular member and tosaid electrode assembly and 'forming substantially the -sole -supportlfor said lelectrode assembly, and -said lead-ins and said tubularmembers `forming the `sole direct current lconcluctors into -saidenvelope.

4. An elect-ron tube, `comprising an envelope including at least twocoaxial-metallic tubular members Yone within the other, the inner voneof said .tubular members having iends extending beyond the outer tubularmember, means connecting inner end portions of said tubular members invacuum tight manner, the other end of said inner member being sealedvacuum tight, said envelope including'a hollow Ydielectric body:port-ion through which said 'tubular members extend, means joining saiddielectric bod-y portion vacuum tight to said outer tubular memberintermediate the ends thereof, a cathode, an anode including a cavityresonator adjacent `said cathode, a second cavity resonator`electrically and thermal-ly closely coupled 'to said anode, and meansconnected --to said second cavity resonator and to said outer tubularmember supporting the former from the latter, said means forming ahighly conduct-ive thermal -path and closely thermally coupled withsaidsecond cavity resonator and said outer Itubular member.

5. An electron tube, comprising an lenvelope including a dielectricportion forming an enclosure, -a cathode and an anode including aAtirstkcavity resonator adjacent said cathode in vsaid enclosure, means`for tuning sai-d -first cavity resonator Iinclud-ing a second cavityresonator closely electrically coupled to -the first cavity resonatorand Vclosely 'thermally coupled 'to said anode, coaxial concentrictubular members forming a reentrant portion of said envelope, the innerof said tubular members being open to the interior of said envelope vandsealed to the atmosphere, means joining said tubular members in airtight relation, and a highly thermally conductive support memberconnected to said secon-d cavity resonator and to one of said tubularmembers, said one tubular member being highly thermally conductive andhaving a portion extending outwardly of said envelope.

6. An electron tube,vcompr.ising an envelope including a dielectricportion forming anenclosure, a cathode and an 4anode block including afirst cavity resonator adjacent said cathode in -said enclosure, meansfor tuning said first lcavity resonator and `cooling said anode blockincluding a second cavity resonator connected to said anode block inAgoed 'heat exchange relationship therewith 'and closelyfelectricallycoupled to Asaid first cavity resonator, said last mentioned meansfurther including coaxial concentric `tubular members forming a portionof said 'fenvelope and a highly thermally conductive member connected toone of the tubular members and to said second cavity resonator in goodheat exchange relationship therewith, the inner .one of said tubularmembers being open to the interior 'of said envelope and closed ito theatmosphere, said one'tubular member also being highlythermallyconductive and having Ya portion extending outwardly of said envelope,and means joining said tubular members in air tight relation. n

v7. An electron tube, comprising an envelope including a dielectricportionforming an enclosure, a Vcathode and an anode-block in ysaidenclosure, saidanodetblock in .cluding a first cavity resonator adjacentsaid cathode,

means for tuning said first cavity resonator and cooling said anodeblock including a second cavity resonator and coaxial concentric tubularmembers, said second cavity resonator being connected to said anodeblock in good heat exchange relationship therewith and closelyelectrically coupled with said first cavity resonator, the inner one ofsaid tubular members extending axially through another one of saidtubular members and having one end portion `thereof open to the insideof said enclosure, means sealing the other end of said inner tubularmember to the atmosphere, fiexible means connected to said inner tubularmember and said other tubular member and joining them in air tightrelation with the inner tubular member movable with respect to the othertubular member, a tuning plunger connected to said inner tubular memberand movable therewith and extending into said second cavity resonatorfor tuning the same, and a highly thermally conductive member rigidlyconnecting said other tubular member to said second cavity resonator andsupporting the latter in good heat exchange relationship with said othertubular member, said other tubular member being highly thermallyconductive and having a portion extending outwardly of said envelope.

8. An electron tube, comprising an envelope including a dielectricportion forming an enclosure, a cathode and an anode block in saidenclosure, said anode block including a first cavity resonator adjacentsaid cathode, means for tuning said first cavity resonator and coolingsaid anode block including a second cavity resonator and at least onehighly thermally conductive tubular member, said second cavity resonatorbeing connected to said anode block in good heat exchange relationshipand closely electrically coupled to said first cavity resonator, meansconnecting said second cavity resonator to said tubular member in goodheat exchange relationship within said envelope and supporting saidsecond cavity resonator, said tubular member having a portion extendingoutwardly of said envelope, and means including an exhaust tubulationsealing said tubular member.

9. An electron tube, comprising an envelope including a dielectricportion forming an enclosure, a cathode and an 'anode block in saidenclosure, said anode block including a first cavity resonator adjacentsaid cathode, means for tuning said first cavity resonator and coolingsaid anode block including a second cavity resonator and at least onehighly thermally conductive tubular member, said second cavity resonatorbeing connected to said anode block in good heat exchange relationshipand closely electrically coupled to said first cavity resonator, meansconnecting said second cavity resonator to said tubular member in goodheat exchange relationship within said envelope and supporting saidsecond cavity resonator, said tubular member having a portion extendingoutwardly of said envelope, means including an exhaust tubulationsealing said tubular member, and a plurality of lead-ins for supplyingan input to said anode and cathode and connected thereto and extendingthrough the wall of said envelope adjacent said tubular member.

10. An electron tube, comprising an envelope including a dielectricportion forming an enclosure, a cathode and an anode block in saidenclosure, said anode block including a first cavity resonator adjacentsaid cathode, means for tuning said first cavity resonator and coolingsaid anode block including a second cavity resonator and at least onehighly thermally conductive tubular member, said second cavity resonatorbeing connected to said anode block in good heat exchange relationshipand closely electrically coupled to said first cavity resonator, meansconnecting said second cavity resonator to `said tubular member in goodheat exchange relationship within said envelope and sup-porting saidsecond cavity resonator, said tubular member having a portion extendingoutwardly of said envelope, means including an exhaust tabulationsealing said tubular member, means for modu- 8 lating said second cavityincluding an electron gun, said electron gun including a plurality ofelectrodes mounted on said second cavity resonator, and a plurality ofleadins for supplying an input to said anode and cathode and electrodes,said lead-ins all extending through the wall of said envelope adjacentsaid tubular member.

1l. An electron device, comprising an envelope including a dielectricportion forming an enclosure, a cathode and an anode block in saidenclosure, said anode block including a first cavity resonator adjacentsaid cathode, means for tuning said first cavity resonator and coolingsaid anode block including a second cavity resonator and coaxialconcentric tubular members, said second cavity resonator being connectedto said anode block in good heat exchange relationship therewith andciosely electrically coupled with said first cavity resonator, the innerone of said tubular members extending axially through another one ofsaid tubular members and having one end portion thereof open to theinside of said enclosure, means sealing the other end of said innertubular member to the atmosphere, liexible means connected to said innertubular member and said other tubular member and joining them in airtight relation with the inner tubular member movable with respect to theother tubular member, a tuning plunger connected to said inner tubularmember and movable therewith and extending into said second cavityresonator, and a highly thermally conductive member rigidly connectingsaid other tubular member to said second cavity resonator and supportingthe latter in good heat exchange relationship with said other tubularmember, said other tubular member being highly thermally conductive andhaving a portion extending outwardly of said envelope.

12. An electron tube, comprising an envelope including a dielectricportion forming an enclosure, a cathode and an anode block in saidenclosure, said anode block including a first cavity resonator adjacentsaid cathode, means for tuning said first cavity resonator and coolingsaid anode block including a second cavity resonator and coaxialconcentric tubular members, said second cavity resonator being connectedto said anode block in good heat exchange relationship therewith andolosely electrically coupled with said rst cavity resonator, the innerone of said tubular members extending axially through another one ofsaid tubular members and having one end portion thereof open to theinside of said enclosure, means sealing the other end of said innertubular member to the atmosphere, liexible means connected to said innertubular member and said other tubular member and joining them in airtight relation with the inner tubular member movable with respect to theother tubular member, a tuning plunger connected to said inner tubularmember and movable therewith and extending into said second cavityresonator for tuning the same, a highly thermally conductive memberrigidly connecting said other tubular member to said second cavityresonator and supporting the latter in good heat exchange relationshipwith said other tubular member, said other tubular member being highlythermally conductive and having a portion extending outwardly of saidenvelope, means for modulating said second cavity resonator including anelectron gun, said electron gun including a plurality of electrodesmounted on said second cavity resonator, and a plurality of lead-insconnected to said anode, cathode and electrodes for supplying an inputthereto, said lead-ins being sealed through said envelope wall adjacentsaid other tubular member.

13. An electron tube, comprising an envelope including a dielectricportion forming an enclosure, a cathode and an anode block in saidenclosure, said anode block including a first cavity resonator adjacentsaid cathode, means for tuning said first cavity resonator and coolingsaid anode block including a second cavity resonator and at least onehighly thermally conductive tubular member, said second cavity resonatorbeing conected to said anode block in good heat exchange relationshipand closely electrically coupled to said rst cavity resonator, amasincluding an exhaust tubulation sealing said tubular memsive highlythermally conductive yoke supporting said secber.

ond cavity resonator and connected thereto in good heat exchangerelationship, said yoke having an aperture Refelenfes Cited in the me 0fthis Patent formed therethrough, said tubular member extending 5 UNITEDSTATES PATENTS through said aperture and connected to said yoke in goodheat exchange relationship, said tubular member Iilcln gli? having aportion extending outwardly of sald envelope, 616,038 Hansen Oct' 28,1952 said envelope including a portion of relatively low thermalconductivity joined to said tubular member, and means l0

